<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>双飞翼三栏布局</title>
  <style>
  #main div{
    height: 300px;
  }
  #left,#right,#middle{
    float: left;
  }
  #left{
    width: 200px;
    margin-left: -100%;
    background: red;
  }
  #right{
    width: 200px;
    margin-left: -200px;
    background: green;
  }
  #middle{
    width: 100%;
    background: orchid;
  }
  #middle .content{
    margin: 0 200px;
    background: orange;
  }
  </style>
</head>
<body>
  <div id="main">
    <div id="middle">
      <div class="content">middle</div>
    </div>
    <div id="left">left</div>
    <div id="right">right</div>
  </div>
</body>
</html>